Dishwashers conventionally use a rinse additive, or wetting agent, to enhance the sheeting of water from the dishes, glasses, and other objects being washed The rinse additive aids in drying the objects, and helps to prevent water spots on the objects.
Many factors affect drying and spotting of objects in a dishwasher. For example, drying and spotting of the objects is dependent upon water temperature, the presence of dissolved solids in the rinse water, the type of detergent used during the wash cycle, and the amount of detergent carried over from the wash cycle into the final rinse. The material from which the objects are made also affects drying and spotting. For example, plastic requires a greater quantity of rinse additive than glass or porcelain. Also, the dishwasher tub material, normally plastic or porcelain, has an effect on drying. Since consumers perceive dryness and spotting in different ways, it is desirable to allow the consumer to select the amount of rinse additive to be used.